Method and apparatus for setting a happy bit on an E-DCH dedicated physical control channel

ABSTRACT

A wireless transmit/receive unit (WTRU) determines (1) whether the WTRU is transmitting as much scheduled data as allowed by a current Serving_Grant, (2) whether the WTRU has enough power to transmit at higher data rate, and (3) based on a same power offset as a currently selected E-DCH transport format combination (E-TFC), whether total E-DCH buffer status (TEBS) would require more than predetermined period to be transmitted with the current Serving_Grant.times.a ratio of active processes to a total number of processes. If criteria (1)-(3) are met, the WTRU sets the happy bit to “unhappy.” If MAC-i/is is configured, the WTRU evaluates criteria (2) by identifying an E-TFC that has a transport block size at least x bits larger than a transport block size of the currently selected E-TFC, and determining whether the identified E-TFC is supported based on a same power offset as the currently selected E-TFC.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/487,370 filed Jun. 18, 2009; which claims the benefit of U.S.Provisional Patent Application No. 61/074,212 filed Jun 20, 2008, and61/089,277 filed Aug 15, 2008, the contents of which are herebyincorporated by reference herein.

FIELD OF INVENTION

This application is related to wireless communications.

BACKGROUND

The third generation partnership project (3GPP) high speed uplink packetaccess (HSUPA) employs a mechanism known as “happy bit” to allow awireless transmit/receive unit (WTRU) to indicate to the network whetherthe uplink data rate allocated to the WTRU is sufficient or not giventhe amount of data in the WTRU buffer. The happy bit is included in anenhanced dedicated channel (E-DCH) dedicated physical control channel(E-DPCCH) for every E-DCH transmissions.

A radio resource control (RRC) entity configures a medium access control(MAC) entity with the duration Happy_Bit_Delay_Condition. The WTRUevaluates the current grant relative to the total E-DCH buffer status(TEBS) during this duration after application of an E-DCH transportformat combination (E-TFC) selection. In accordance with the 3GPPspecification 25.321 V8.2.0, for every E-DCH transmission, the happy bitis set to “unhappy” if the following three criteria are met:

(1) The WTRU is transmitting as much scheduled data as allowed by thecurrent Serving_Grant in E-TFC selection;

(2) The WTRU has enough power available to transmit at a higher datarate; and

(3) Based on the same power offset as the one selected in E-TFCselection to transmit data in the same transmission time interval (TTI)as the happy bit, TEBS would require more than Happy_Bit_Delay_Conditionms to be transmitted with the current Serving_Grant.times.the ratio ofactive processes to the total number of processes.

If the above three criteria are not met, the happy bit shall be set to“happy.” The received happy bit may be used by the network to determinewhether the serving grant should be increased, decreased, or leftunchanged.

In accordance with the 3GPP specification, the WTRU will only set thehappy bit to “unhappy” if the WTRU has sufficient transmission power toinclude at least one additional radio link control (RLC) protocol dataunit (PDU) in an E-TFC. In other words, the WTRU sets the happy bit to“unhappy” only if there is an E-TFC that may accommodate one additionalRLC PDU compared to the one used when the happy bit is determined andthe E-TFC is in a “supported state.” This restriction has beenintroduced to prevent the WTRU from requesting a higher data rate fromthe network while the WTRU would anyway be unable to increase its datarate due to power restrictions.

With the introduction of flexible RLC PDU size and segmentation at theMAC layer for the HSUPA in 3GPP Release 8, restriction that the WTRU hasto be capable of transmitting at least one additional RLC PDU in anE-TFC is needlessly restrictive because the WTRU may increase the datarate by transmitting a segment of an additional RLC PDU or just increasethe size of the RLC PDU. With this restriction the WTRU will not set thehappy bit to “unhappy” even though the WTRU can increase the data rateby transmitting a fraction of an additional RLC PDU or by increasing thesize of subsequent RLC PDUs. Thus, under the conventional 3GPPspecification, the uplink data rate is not maximized.

Under the current 3GPP specification, if the serving grant becomes toosmall to allow transmission of a single PDU from any scheduled MAC-dflow or if the serving grant is too small to allow transmission of asingle PDU from any scheduled MAC-d flow and TEBS becomes larger thanzero, the transmission of scheduling information is triggered. With theintroduction of MAC segmentation for the HSUPA, it is unlikely that theWTRU is unable to transmit any data when the serving grant falls below acertain value because with the introduction of MAC segmentation the WTRUmay always be able to transmit a segment of an RLC PDU even if the grantis too small to allow the transmission of a full RLC PDU. Therefore, theabove scheduling information triggering criterion is not desirable andmay result in excessive transmission of the scheduling information.

SUMMARY

A method and an apparatus for setting a happy bit on an E-DPCCH aredisclosed. A WTRU determines (1) whether the WTRU is transmitting asmuch scheduled data as allowed by a current Serving_Grant in E-TFCselection, (2) whether the WTRU has enough power available to transmitat a higher data rate, and (3) based on a same power offset as acurrently selected E-TFC for transmission in a same TTI as the happybit, whether TEBS would require more than Happy_Bit_Delay_Condition msto be transmitted with the current Serving_Grant x a ratio of activeprocesses to a total number of processes. On a condition that thecriteria (1) through (3) are met, the WTRU sets the happy bit to“unhappy.” On a condition that a medium access control entity for E-DCH(MAC-i/is) is configured, the WTRU evaluates the criteria (2) byidentifying an E-TFC that has a transport block size at least x bitslarger than a transport block size of the currently selected E-TFC, anddetermining whether the identified E-TFC is supported based on a samepower offset as the currently selected E-TFC. The value x may be apredetermined value or may be configured by a higher layer.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 is a flow diagram of an example process for determining whether aWTRU has enough power available to transmit at a higher data rate andsetting a happy bit in accordance with a first embodiment;

FIG. 2 is a flow diagram of an example process for determining whether aWTRU has enough power available to transmit at a higher data rate andsetting a happy bit in accordance with a second embodiment;

FIG. 3 is a flow diagram of an example process for determining whether aWTRU has enough power available to transmit at a higher data rate andsetting a happy bit in accordance with a third embodiment;

FIG. 4 is a flow diagram of an example process for determining whether aWTRU has enough power available to transmit at a higher data rate andsetting a happy bit in accordance with a fourth embodiment;

FIG. 5 is a flow diagram of an example process for determining whether aWTRU has enough power available to transmit at a higher data rate andsetting a happy bit in accordance with a fifth embodiment; and

FIG. 6 is a block diagram of an example WTRU.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “WTRU” includes but is notlimited to a user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a computer, or any other type of user device capable ofoperating in a wireless environment. When referred to hereafter, theterminology “Node B” includes but is not limited to a base station, asite controller, an access point (AP), or any other type of interfacingdevice capable of operating in a wireless environment.

For every E-DCH transmission, a WTRU sets a happy bit to “unhappy” ifthe three criteria are met, (i.e., (1) the WTRU is transmitting as muchscheduled data as allowed by the current Serving_Grant in E-TFCselection, (2) the WTRU has enough power available to transmit at ahigher data rate; and (3) based on the same power offset as the oneselected in E-TFC selection to transmit data in the same TTI as thehappy bit, TEBS would require more than Happy_Bit_Delay_Condition ms tobe transmitted with the current Serving_Grant.times.the ratio of activeprocesses to the total number of processes).

FIG. 1 is a flow diagram of an example process 100 for determiningwhether a WTRU has enough power available to transmit at a higher datarate and setting a happy bit in accordance with a first embodiment. Incase MAC-i/is (MAC entity for handling E-DCH transmissions whichsupports MAC segmentation) is configured by a higher layer, (i.e., RLCPDU segmentation at the MAC layer is supported), a WTRU identifies asmallest E-TFC that allows transmission of more data than the currentE-TFC (step 102). The current E-TFC is the E-TFC selected fortransmission in the same TTI as the happy bit whose value is to bedetermined The additional data may be from any logical channel that doesnot belong to a non-scheduled MAC-d flow. The WTRU then determines,based on the same power offset as the current E-TFC, whether theidentified E-TFC is supported, (i.e., whether the identified E-TFC maybe transmitted considering the maximum allowed power of the WTRU), (step104). If the identified E-TFC is supported, the WTRU determines that theWTRU has enough power available to transmit at a higher data rate. TheWTRU determines whether the other two criteria, (criteria (1) and (3)),are met (step 106). If so, the WTRU sets the happy bit to “unhappy”(step 108). If the identified E-TFC is not supported, or if the othertwo criteria are not met, the WTRU sets the happy bit to “happy” (step110).

It should be noted that the method steps in FIG. 1 may be performed indifferent order. For example, step 106 may be performed before step 102.

FIG. 2 is a flow diagram of an example process 200 for determiningwhether a WTRU has enough power available to transmit at a higher datarate and setting a happy bit in accordance with a second embodiment. Incase MAC-i/is is configured by a higher layer, a WTRU determines ifthere is any E-TFC larger than the current E-TFC in a supported state inthe configured E-DCH transport block size table (step 202). The currentE-TFC is the E-TFC selected for transmission in the same TTI as thehappy bit whose value is to be determined If there is any E-TFC largerthan the current E-TFC in a supported state in the configured E-DCHtransport block size table, the WTRU determines that the WTRU has enoughpower available to transmit at a higher data rate. The WTRU determineswhether the other two criteria, (i.e., criteria (1) and (3)), are met(step 204). If so, the WTRU sets the happy bit to “unhappy” (step 206).If there is no E-TFC larger than the current E-TFC in a supported statein the configured E-DCH transport block size table, or if the other twocriteria are not met, the WTRU sets the happy bit to “happy” (step 208).

It should be noted that the method steps in FIG. 2 may be performed indifferent order. For example, step 204 may be performed before step 202.

FIG. 3 is a flow diagram of an example process 300 for determiningwhether a WTRU has enough power available to transmit at a higher datarate and setting a happy bit in accordance with a third embodiment. Incase MAC-i/is is configured by a higher layer, a WTRU identifies anE-TFC that allows the WTRU to transmit at least x byte(s) (or bits) morethan the current E-TFC (step 302). The current E-TFC is the E-TFCselected for transmission in the same TTI as the happy bit whose valueis to be determined The additional data may be from any logical channelthat does not belong to a non-scheduled MAC-d flow. Optionally, the WTRUmay take into account the possible need for additional MAC overhead incalculating the additional data, (e.g., if the additional data wouldhave to come from a different RLC PDU than the last segmented one).

The WTRU then determines, based on the same power offset as the currentE-TFC, whether the identified E-TFC is supported (step 304). If theidentified E-TFC is supported, the WTRU determines that the WTRU hasenough power available to transmit at a higher data rate. The WTRUdetermines whether the other two criteria, (i.e., criteria (1) and (3)),are met (step 306). If so, the WTRU sets the happy bit to “unhappy”(step 308). If the identified E-TFC is not supported, or if the othertwo criteria are not met, the WTRU sets the happy bit to “happy” (step310).

The value x may be a fixed pre-determined value, (e.g., 1). The value xmay be signaled by a higher layer. The value x may correspond to a“minimum MAC segment size” if such parameter is defined. The value x maycorrespond to the minimum RLC PDU size or a function thereof. The valuex may correspond to a percentage increase in the size of the current RLCPDU size, (i.e., an X % increase in RLC data rate). The value x maycorrespond to the minimum allowed transport block size or the minimumreference E-TFC or a function thereof, (e.g., a defined fraction of theminimum transport block size). The value x may correspond to the minimumvalue of the minimum E-TFC set or a function thereof.

Alternatively, the value x may be the minimum value between a percentageof the size of the current E-TFC and a fixed threshold. The percentageand/or the threshold may be pre-defined or signaled by RRC. Thethreshold may correspond to the minimum RLC PDU size, the smallest RLCPDU size, or any other signaled value. Alternatively, the value x may bethe minimum value between 1) the difference in size in bits between theE-TFC that is n indices above the current E-TFC in an E-DCH transportblock size table and the current E-TFC, and 2) a fixed threshold. Thevalue of n and/or the threshold may be pre-defined or signaled by RRC.The threshold may correspond to the minimum RLC PDU size, the smallestRLC PDU size, or any other signaled value.

Alternatively, the value x may be set depending whether the minimumimprovement of x byte(s) or bits is absolute or relative. For instance,the WTRU may determine that the minimum improvement of x byte(s) or bitsis relative if the size of the current E-TFC is below a threshold, ifthe current E-TFCI is below a threshold, if the current WTRU powerheadroom (UPH) is below a threshold, or if the current serving grant isbelow a threshold. The threshold values may be pre-defined or signaled.

In case the minimum improvement of x byte(s) or bits is relative, thevalue x may be set to a percentage of the size of the current E-TFC, orthe difference in bits between the E-TFC that is n indices above thecurrent E-TFC in the E-DCH transport block size table, and the currentE-TFC. The value of n may be pre-defined, (e.g., n=1), or signaled.

Conversely, the WTRU may determine that the minimum improvement of xbyte(s) or bits is absolute if the size of the current E-TFC is above athreshold, if the current E-TFCI is above a threshold, if the currentWTRU power headroom (UPII) is above a threshold, or if the currentserving grant is above a threshold. The threshold values may bepre-defined or signaled.

In case the minimum improvement of x byte(s) or bits is absolute, thevalue of x may be set to a pre-determined or signaled value. Thesignaled value may be the minimum RLC PDU size, the smallest RLC PDUsize, or any other signaled value. Alternatively, the value of x may bethe difference in bits between the E-TFC that is n indices above thecurrent E-TFC in the configured E-DCH transport block size table, wherethe value of n may be predefined, (e.g., n=1), or signaled.

Alternatively, the value x may be the maximum value between a definedthreshold and the difference in size in bits between the E-TFC that is nindices above the current E-TFC in the configured E-DCH transport blocksize table and the current E-TFC. The threshold may be pre-defined orsignaled by RRC. The threshold may correspond to the minimum RLC PDUsize, the smallest RLC PDU size, or any other signaled value and n maybe a predefined value, (i.e., n=1), or signaled.

It should be noted that the method steps in FIG. 3 may be performed indifferent order. For example, step 306 may be performed before step 302.

FIG. 4 is a flow diagram of an example process 400 for determiningwhether a WTRU has enough power available to transmit at a higher datarate and setting a happy bit in accordance with a fourth embodiment. Incase MAC-i/is is configured by a higher layer, a WTRU determines if thelatest WTRU transmission power headroom measurement is lower than athreshold (step 402). The WTRU transmission power headroom is the ratioof the maximum WTRU transmission power and the corresponding dedicatedphysical control channel (DPCCH) code power, which is defined in 3GPP TS25.215 V8.2.0.

If the latest transmission WTRU power headroom measurement is not belowthe threshold, the WTRU determines that the WTRU has enough poweravailable to transmit at a higher data rate. The WTRU determines whetherthe other two criteria, (i.e., criteria (1) and (3)), are met (step404). If so, the WTRU sets the happy bit to “unhappy” (step 406). If thelatest WTRU transmission power headroom measurement is below thethreshold, or if the other two criteria are not met, the WTRU sets thehappy bit to “happy” (step 408).

The threshold may be pre-determined or signaled by a higher layer.Alternatively, the threshold may be dependent on the granularity of therelative grant (given the parameters 3-index step threshold and 2-indexstep threshold) at the conventional scheduled grant. Alternatively, thethreshold may be a function of the current serving grant. For instance,the threshold may be the sum of the current serving grant (in terms ofpower ratio) and a factor times the grant increase resulting from arelative grant “UP” command sent from the network.

It should be noted that the method steps in FIG. 4 may be performed indifferent order. For example, step 404 may be performed before step 402.

FIG. 5 is a flow diagram of an example process 500 for determiningwhether a WTRU has enough power available to transmit at a higher datarate and setting a happy bit in accordance with a fifth embodiment. Incase MAC-i/is is configured by a higher layer, a WTRU determines if theE-TFC obtained by applying E-TFC selection function assuming that thenetwork sent a relative grant “UP” command at the current TTI (with thesame power offset as the current E-TFC) would be smaller than or equalto the maximum supported E-TFC, while the E-TFC selected fortransmission in the same TTI as the happy bit is lower than (oralternatively lower than or equal to) the maximum supported E-TFC (step502).

If the determination is positive, the WTRU determines that the WTRU hasenough power available to transmit at a higher data rate. The WTRUdetermines whether the other two criteria, (criteria (1) and (3)), aremet (step 504). If so, the WTRU sets the happy bit to “unhappy” (step506). If the determination is negative, or if the other two criteria arenot met, the WTRU sets the happy bit to “happy” (step 508).

It should be noted that the method steps in FIG. 5 may be performed indifferent order. For example, step 504 may be performed before step 502.

In accordance with a sixth embodiment, in case MAC-i/is is configured bya higher layer if a serving grant becomes too small to allowtransmission of a single PDU from any scheduled MAC-d flow or if theserving grant is too small to allow transmission of a single PDU fromany scheduled MAC-d flow and TEBS becomes larger than zero, thetransmission of scheduling information may not be triggered. In caseMAC-i/is is not configured by a higher layer, the scheduling informationmay still be triggered in that situation.

FIG. 6 is a block diagram of an example WTRU 600. The WTRU 600 includesa transmitter 601, a receiver 602, and a controller 604. The controller604 is configured to set the happy bit in accordance with any one ofembodiments disclosed above. For example, the controller 604 isconfigured to determine (1) whether the WTRU is transmitting as muchscheduled data as allowed by a current Serving_Grant in E-TFC selection,(2) whether the WTRU has enough power available to transmit at a higherdata rate, and (3) based on a same power offset as a currently selectedE-TFC for transmission in a same TTI as the happy bit, whether TEBSwould require more than Happy_Bit_Delay_Condition ms to be transmittedwith the current Serving_Grant.times.a ratio of active processes to atotal number of processes, and set the happy bit to “unhappy” if thecriteria (1) through (3) are met; otherwise set the happy bit to“happy.” The controller 604 is configured to, in order to evaluate thecriteria (2), identify an E-TFC that has a transport block size at leastx bits larger than a transport block size of the currently selectedE-TFC on a condition that a MAC-i/is is configured, and determinewhether the identified E-TFC is supported based on a same power offsetas the currently selected E-TFC.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth™. module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

What is claimed:
 1. A method for setting a happy bit on an enhanceddedicated channel (E-DCH) dedicated physical control channel (E-DPCCH)in a wireless transmit/receive unit (WTRU), the method comprising:determining whether predetermined criteria are met and setting the happybit to “unhappy” on a condition that the criteria are met, wherein whenE-DCH improved medium access control (MAC-i/is) is configured and mediumaccess control (MAC) segmentation is supported the criteria includesdetermining whether the WTRU has enough power available to transmit at ahigher data rate and determining whether the WTRU has enough poweravailable to transmit at the higher data rate comprises: identifying anE-DCH transport format combination (E-TFC) that has a transport blocksize at least x number of bits larger than a transport block size of acurrently selected E-TFC selected for transmission in a sametransmission time interval (TTI) as the happy bit; and determiningwhether the identified E-TFC is supported based on a same power offsetas the currently selected E-TFC.
 2. The method of claim 1, wherein thevalue x is configured by a higher layer.
 3. The method of claim 1,wherein the value x corresponds to one of a minimum MAC segment size, apercentage increase in a size of a current radio link control (RLC)protocol data unit (PDU) size, a minimum allowed transport block size,or a minimum value of a minimum E-TFC set.
 4. The method of claim 1,wherein the value x is a minimum value between a percentage of a size ofthe currently selected E-TFC and a fixed threshold.
 5. The method ofclaim 1, wherein the value x is a minimum value between a difference insize in bits between an E-TFC that is n indices above the currentlyselected E-TFC in an E-DCH transport block size table and the currentlyselected E-TFC, and a fixed threshold.
 6. The method of claim 1, whereinx is a predetermined value that corresponds to a segmented radio linkcontrol (RLC) protocol data unit (PDU) size.
 7. The method of claim 1,wherein x is a predetermined value and is unrelated to a smallest radiolink control (RLC) protocol data unit (PDU) size.
 8. A wirelesstransmit/receive unit (WTRU) configured to set a happy bit on anenhanced dedicated channel (E-DCH) dedicated physical control channel(E-DPCCH), the WTRU comprising: a transceiver configured to transmit thehappy bit on the E-DPCCH; and a controller configured to determinewhether predetermined criteria are met and set the happy bit to“unhappy” on a condition that the criteria are met, wherein when E-DCHimproved medium access control (MAC-i/is) is configured and mediumaccess control (MAC) segmentation is supported the criteria includeswhether the WTRU has enough power available to transmit at a higher datarate and determining whether the WTRU has enough power available totransmit at the higher data rate comprises the controller beingconfigured to: identify an E-DCH transport format combination (E-TFC)that has a transport block size at least x number of bits larger than atransport block size of a currently selected E-TFC selected fortransmission in a same transmission time interval (TTI) as the happybit; and determine whether the identified E-TFC is supported based on asame power offset as the currently selected E-TFC.
 9. The WTRU of claim8, wherein the value x is configured by a higher layer.
 10. The WTRU ofclaim 8, wherein the value x corresponds to one of a minimum MAC segmentsize, a minimum radio link control (RLC) protocol data unit (PDU) size,a percentage increase in a size of a current RLC PDU size, a minimumallowed transport block size, or a minimum value of a minimum E-TFC set.11. The WTRU of claim 8, wherein the value x is a minimum value betweena percentage of a size of the currently selected E-TFC and a fixedthreshold.
 12. The WTRU of claim 8, wherein the value x is a minimumvalue between a difference in size in bits between an E-TFC that is nindices above the currently selected E-TFC in an E-DCH transport blocksize table and the currently selected E-TFC, and a fixed threshold. 13.The WTRU of claim 8, wherein x is a predetermined value that correspondsto a segmented radio link control (RLC) protocol data unit (PDU) size.14. The WTRU of claim 8, wherein x is a predetermined value and isunrelated to a smallest radio link control (RLC) protocol data unit(PDU) size.